I am using a flyback converter (LT3511)to generate +70V and -70V to power the LTC6090(High Voltage Opamp), the circuit works fine when the opamp is not connected but gives zero output when the opamp is connected. I am using 4 opamps in total.

Hello Arnav ,

Have you checked if the pin config on the board matches the pin config of the LT3511?
Please also make sure that when you solder the op amp, no pins are shorting to GND especially EN/UVLO and SW pin (check if these pins are shorted to GND).

Regards,
Ken

The issue I am facing is when the operational amplifiers ( LTC6090) not soldered on the board the output of the LT3511(Flyback converter) is as expected (+70V &-70V) but when I solder the operational amplifiers ( LTC6090) on the board there is almost zero volts output from the LT3511( Flyback converter)

Hello Arnav,

I simulated your schematic on LT Spice and got the same results. Output of LT3511 is good when LTC6090 is not connected and its almost 0 when LTC6090 is connected.
I double checked the circuit and found out that SW and Vin might be connected wrong. Based on datasheet, SW pin should be connected on the polarized terminal (pin 3) of the primary winding of 750311692 transformer but on your schematic, it is connected on the non polarized terminal (pin4).

Simulation showed a voltage of +/-20V on the output of LT3511 when SW is connected on the polarized terminal (pin 3). I'm not sure yet why it did not reach +/-70V(will try to figure it out further) but its totally different output compared to when SW is connected on the non polarized terminal(pin 4).


original schematic:

modified schematic (SW connected on the polarized terminal)


Can you check and confirm on the actual board if SW is connected on the non polarized terminal (pin4)? If yes, can you try to connect it on the polarized terminal (pin3) and also connect Vin on the non polarized terminal (pin4) as shown on working LTspice model and let us know the results.

Also, as checked in datasheet(page 10) this configuration of LT3511 (12V to +/-70V flyback converter) can only handle 4mA of load. Please also check actual supply current at LTC6090 on your circuit. 


I attached a folder containing my .asc file and the models of the diode used for reference.

Regards,
Kenneth

1200.LT3511_LTC6090_simulation.zip

Hello Arnav,

I simulated your schematic on LT Spice and got the same results. Output of LT3511 is good when LTC6090 is not connected and its almost 0 when LTC6090 is connected.
I double checked the circuit and found out that SW and Vin might be connected wrong. Based on datasheet, SW pin should be connected on the polarized terminal (pin 3) of the primary winding of 750311692 transformer but on your schematic, it is connected on the non polarized terminal (pin4).

Simulation showed a voltage of +/-20V on the output of LT3511 when SW is connected on the polarized terminal (pin 3). I'm not sure yet why it did not reach +/-70V(will try to figure it out further) but its totally different output compared to when SW is connected on the non polarized terminal(pin 4).


original schematic:

modified schematic (SW connected on the polarized terminal)


Can you check and confirm on the actual board if SW is connected on the non polarized terminal (pin4)? If yes, can you try to connect it on the polarized terminal (pin3) and also connect Vin on the non polarized terminal (pin4) as shown on working LTspice model and let us know the results.

Also, as checked in datasheet(page 10) this configuration of LT3511 (12V to +/-70V flyback converter) can only handle 4mA of load. Please also check actual supply current at LTC6090 on your circuit. 


I attached a folder containing my .asc file and the models of the diode used for reference.

Regards,
Kenneth

1200.LT3511_LTC6090_simulation.zip

Hello Arnav ,

Any update on this thread? Have you successfully made the circuit work?
Appreciate your response.

Thanks,
Ken